Systemic vitamin exposure

Estimates of Possible Systemic Vitamin Exposure Using the UHMWPE Articulation Components for Total Joint Arthroplasty... 

Lead is toxic to the kidney, cardiovascular system, developiag red blood cells, and the nervous system. The toxicity of lead to the kidney is manifested by chronic nephropathy and appears to result from long-term, relatively high dose exposure to lead. It appears that the toxicity of lead to the kidney results from effects on the cells lining the proximal tubules. Lead inhibits the metaboHc activation of vitamin D in these cells, and induces the formation of dense lead—protein complexes, causing a progressive destmction of the proximal tubules (13). Lead has been impHcated in causing hypertension as a result of a direct action on vascular smooth muscle as well as the toxic effects on the kidneys (12,13). 

An example of this methodology was its use in the synthesis of vitamin Be, pyridoxine 12. Cycloaddition of oxazole 9, prepared from ethyl A-acetylalanate and P2O5, with maleic anhydride initially gave 10. Upon exposure to acidic ethanol, the oxabicyclooctane system fragments to afford pyridine 11. Reduction of the ester substituents with LiAlIU generated the desired product 12. 

Effects on Vitamin D Metabolism. Lead interferes with the conversion of vitamin D to its hormonal form, 1,25-dihydroxyvitamin D. This conversion takes place via hydroxylation to 25-hydroxyvitamin D in the liver followed by 1-hydroxylation in the mitochondria of the renal tubule by a complex cytochrome P-450 system (Mahaffey et al. 1982 Rosen and Chesney 1983). Evidence for this effect comes primarily from studies of children with high lead exposure. 

The precise mechanism of dimethylhydrazine toxicity is uncertain. In addition to the contact irritant effects, the acute effects of dimethylhydrazine exposure may involve the central nervous system as exemplified by tremors and convulsions (Shaffer and Wands 1973) and behavioral changes at sublethal doses (Streman et al. 1969). Back and Thomas (1963) noted that the deaths probably involve respiratory arrest and cardiovascular collapse. The central nervous system as a target is consistent with the delayed latency in response reported for dimethylhydrazine (Back and Thomas 1963). There is some evidence that 1,1-dimethylhydrazine may act as an inhibitor of glutamic acid decarboxylase, thereby adversely affecting the aminobutyric acid shunt, and could explain the latency of central-nervous-system effects (Back and Thomas 1963). Furthermore, vitamin B6 analogues that act as coenzymes in the aminobutyric acid shunt have been shown to be effective antagonists to 1,1-dimethylhydrazine toxicity (reviewed in Back and Thomas 1963). 

The nervous system is the most sensitive target for cyanide toxicity, partly because of its high metabolic demands. High doses of cyanide can result in death via central nervous system effects, which can cause respiratory arrest. In humans, chronic low-level cyanide exposure through cassava consumption (and possibly through tobacco smoke inhalation) has been associated with tropical neuropathy, tobacco amblyopia, and Leber s hereditary optic atrophy. It has been suggested that defects in the metabolic conversion of cyanide to thiocyanate, as well as nutritional deficiencies of protein and vitamin B12 and other vitamins and minerals may play a role in the development of these disorders (Wilson 1965). 

While most of these treatments are on a very shaky scientific footing, desperate people still try them. History has shown that when scientific medicine leaves a vacuum, a host of alternative practitioners will rush in to fill it. These people claim to have the answers that have somehow eluded mainstream researchers. Such as the benefits of the Harmony Token, a colored disk you wear around your neck its manufacturer claims that it resupplies minerals, vitamins, and amino acids with the color that has been stripped away by exposure to electromagnetic radiation. Our bodies, apparently, do not recognize these colorless substances and, as a consequence, our immune systems are weakened. The Harmony Token utilizes 2,800 colors to rebuild and repair the body at the cellular level and allows victims of rheumatoid arthritis to resume normal lives. Testimonials proclaim the disk s astonishing powers it improves gas mileage and reduces car emissions it makes racehorses run faster it cures migraines. It also makes me wonder about people s sanity. 

Although exposure to nitrous oxide is associated with an acute vitamin B12 deficiency due to oxidation of the vitamin, the serum vitamin B12 concentration remains normal even when measured using a biological system with E. gracilis as the test organism (A6). The organism is apparently able to use both reduced and oxidized forms of the vitamin. 

Vitamin D deficiency remains the most common cause of rickets and osteomalacia in the world, with the exception of the United States and the Scandinavian countries where most dairy products are supplemented with this vitamin. This deficiency can be caused either by dietary habits or by insufficient exposure to ultraviolet light. The same type of symptoms can be observed when there is interruption of the normal vitamin D metabolic pathways due to a number of liver and/or kidney diseases. In addition, a number of inherited factors can lead to different types of vitamin D resistance which require massive supplements of vitamin D and/or minerals. Extensive reviews have been published depicting both the clinical features and their most likely causes, as well as the possible treatments of the different types of clinical disorders resulting from vitamin D deficiencies [113-117], The newly defined role for l,25(OH)2D3 upon the hematopoietic system could also have clinical relevance in bone disorders such as osteoporosis where patients have been shown to possess abnormal T-cell subsets [118]. 

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